A US woman who shot and killed her husband and two adult children before taking her own life is thought to have committed the shocking crime as a result of being ostracised from the religion she was raised in.

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"Thank you for what you've done," she said, speaking not only to locals but to the 2000-odd firefighters from across the country who joined in the effort to save lives and homes in NSW.

Tributes flowed on Friday for pilot David Black, who died when his aircraft crashed while fighting a fire at Wirritin in Budawang National Park, west of Ulladulla.

His was the second life lost in the fires. A 63-year-old man died defending his Central Coast home last Thursday.

Deputy Commissioner Rob Rogers said there was a sense of hiatus at the Rural Fire Service (RFS) headquarters, but dangerous fire weather could hit within days and dozens of fires continued to burn across the state.

"The fact is it's going to take weeks, not days, to get containment on all these fires," he told AAP.

"People do get fatigued - particularly when it's warning after warning going out to the same communities."

No one should be under any illusion that the dire scenarios predicted for Wednesday - like the fear that major fires could merge to form a super fire spanning the Blue Mountains - were over-hyped, he said.

Firefighters had worked "way beyond" the hours they would ordinarily be allowed to put in, forgoing sleep to run risky back-burning operations around the mountains in a bid to avoid catastrophe.

"I genuinely did fear that we were going to lose people in that fire," Mr Rogers said.

"The community tends to view the fact that we didn't have mayhem and destruction by saying, 'Oh, well it didn't happen'.

"Well it didn't happen because a lot of people worked hard to stop it happening."

The federal government has extended its Disaster Recovery Payments of $1000 per adult and $400 per child to bushfire-affected residents in the Wollondilly area, southwest of Sydney.

The region was on emergency alert over the weekend as the Hall Road fire raged, but the blaze has since been contained.